1. Field of the Invention
The invention relates to a diagnostic apparatus and a diagnostic method for a fuel cell and, more particularly, to a diagnostic apparatus and a diagnostic method for diagnosing a state of a fuel cell installed in a moving object as a power source.
2. Description of the Related Art
Heretofore, there has been proposed a fuel cell system of this type which makes a determination on an abnormal operational state such as excessiveness or scarceness of water contained in a fuel cell stack and which performs control to normalize the abnormal operational state (e.g., Japanese Patent Application Laid-Open No. 9-245826). In this system, time-dependent change patterns of a voltage in a cell or cell block constituting the fuel cell stack are measured and stored in advance as to various operational conditions, and a determination on an operational state of the fuel cell stack is made by comparing an actual time-dependent pattern with the stored patterns.
However, if the fuel cell system thus constructed is installed in a vehicle, an operational abnormality of the fuel cell stack during a running state of the vehicle cannot be reproduced easily when the vehicle is stopped. If an operational abnormality occurs in the fuel cell stack while the vehicle is running, a state of the operational abnormality needs to be reproduced so as to have the cause thereof fathomed in a repair shop or the like. However, since operation of the fuel cell stack during stoppage of the vehicle makes it impossible to consume power obtained from the fuel cell stack, the state of the operational abnormality cannot be reproduced. A similar problem crops up during inspection or maintenance for obviating abnormalities or malfunctions as well.